The question is in the title. There's already a similar thread with no replies, but it's in a wrong forum section and is obviously dead. I can't find a meaning of the "_TextureSampleAdd" shader variable. It's documented nowhere. I see that in the default UI shaders it's a 4d vector and that it simply offsets a texure's RGBA values. But why is it used in the 1st place? What is it used for? What does it do when it's added? It's very important to understand it's purpose for any non-Alpha-blended UI shaders. E.g., for additive or multiply blend modes. I'm really confused at which stage I need to use _TextureSampleAdd and how exactly.